They actually have made it to 3.7Ghz, but I put little into this. they use heavily modified systems and liquid nitrogen on hand picked CPUs to get the system stable enough to run CPUID. That is about it. They did the same thing to the old P4 core and made it to 2.8Ghz or more and even had an Athlon 1.4Ghz (thunderbird core) running at 2.4+Ghz. In my opinion, Intel might not make it to the 3Ghz target by the end of the year like they wanted too.
Most CPUs will top out at about 30% below the extreme cooling level. That means the currant core will likely do about 2.6Ghz. They will likely get new steppings out that might make it to 2.8Ghz, but I think they will fail to get 3Ghz. The AthlonXP can make it as high as 2.2Ghz with super cooling, but will likely not see it past 1.67Ghz.
The other thing to note is they will not switch to .09 micron until about 2-3Q 2003. AMD has a few oppertunities here. They will hit a minimum of 2.07Ghz at .13 micron and if they do release the Barton core with SOI at .13 micron they will likely hit 2.4 to 2.5Ghz. IBM says 40% boost, but 20% is more likely. That would give them a model 3200-3400. They might not release the Barton core though if things are looking good for the ClawHammer (which is supposed to be out about the end of the year at model 3400).
Now a system that is 100% stable and opperable at a good speed is better. Tom's did get a hand picked P4 that did do 3Ghz with air cooling (Alpha 8045), but he said the majority need water cooling to reach this level. Most review sites managed 2.6-2.7Ghz with standard air cooling. This IS a nice overclock, but nothing super stellar.
The other thing I thaught was interesting is that to get the overclcoks at Tom's required the use of a DDR board. The RDRAM could not take the higher bus speeds without crippling the memory to 3/4 speed (PC600). So even though he reached 3Ghz, it was with lower score than you could normally get. Now when Intel oficially launches the 533Mhz bus, RDRAM PC1066 might be more avaluable. then you could get an i850 board up to 533Mhz bus and overclock you P4 2.0A to 2.67Ghz by bumping the voltage and switching to 533Mhz bus. That would be a nice overclock.
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